Subaqueous barchan dunes in turbulent shear flow. Part 1. Dune motion

@article{Franklin2011SubaqueousBD,
  title={Subaqueous barchan dunes in turbulent shear flow. Part 1. Dune motion},
  author={Erick de Moraes Franklin and François Charru},
  journal={Journal of Fluid Mechanics},
  year={2011},
  volume={675},
  pages={199 - 222}
}
Experiments are reported on the formation and migration of isolated dunes in a turbulent channel flow. These dunes have a very robust crescentic shape with horns pointing downstream, very similar to that of the barchan dunes observed in deserts at a much larger scale. Their main geometrical and dynamical properties are studied in detail, for four types of grains: the conditions for their formation, their morphology, the threshold shear stress for their motion, their velocity, erosion rate… Expand
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References

SHOWING 1-10 OF 36 REFERENCES
Minimal model for aeolian sand dunes.
We present a minimal model for the formation and migration of aeolian sand dunes in unidirectional winds. It combines a perturbative description of the turbulent wind velocity field above the duneExpand
A scaling law for aeolian dunes on Mars, Venus, Earth, and for subaqueous ripples
Abstract The linear stability analysis of the equations governing the evolution of a flat sand bed submitted to a turbulent shear flow predicts that the wavelength λ at which the bed destabilises toExpand
Selection of the ripple length on a granular bed sheared by a liquid flow
The stability of a granular bed sheared by a liquid flow is investigated using an erosion-deposition model for the moving grains. Extending to arbitrary wave number a previous long wave analysis [F.Expand
Flow effects on the morphology and dynamics of aeolian and subaqueous barchan dunes
[1] Barchans are aeolian sand dunes that form where unidirectional winds blow on firm ground with limited sand supply. Although they have been analyzed for decades, the difficulty of conductingExpand
Turbulent shear flows over low hills
A general analysis is developed for turbulent shear flows over two- and three-dimensional hills with low-slopes which allows for a wide range of upwind velocity profiles, such as those caused byExpand
Bed load transport in turbulent flow at the grain scale: Experiments and modeling
[1] We report an experimental investigation of the motion of bed load particles under steady and spatially uniform turbulent flow above a flat sediment bed of uniform grain size. Using a high-speedExpand
Sediment erosion by Görtler vortices: the scour-hole problem
Experimental results on sediment erosion (scour) by a plane turbulent wall jet, issuing from a sluice gate, are presented which show clearly – it seems for the first time – that the turbulent wallExpand
Selection of dune shapes and velocities Part 2: A two-dimensional modelling
Abstract:We present in this paper a simplification of the dune model proposed by Sauermann et al. which keeps the basic mechanisms but allows analytical and parametric studies. Two kinds of purelyExpand
On the crescentic shape of barchan dunes
Abstract.Aeolian sand dunes originate from wind flow and sand bed interactions. According to wind properties and sand availability, they can adopt different shapes, ranging from huge motion-less starExpand
Shearing flow over a wavy boundary
A theoretical study is made of shearing flows bounded by a simple-harmonic wavy surface, the main object being to calculate the normal and tangential stresses on the boundary. The type of flowExpand
...
1
2
3
4
...